In various applications, integrated coils are used with magnetic field sensors for generating magnetic fields for test or in situ calibration purposes. Such integrated coils are inter alia defined by a coil factor that determines the magnetic field generated per current applied to the coil. In particular, the field generated by the coil and sensed by a magnetic field sensor is based on the coil current multiplied by the coil factor, e.g. averaged over a sensor area of the magnetic field sensor. For a predetermined supply voltage the maximum coil current is obtained by dividing the supply voltage by an ohmic resistance of the coil. For large sensors the coil length becomes very long and hence the resistance of the coil is large. Thus, the maximum generated field achievable with a given supply voltage is limited.
A large sensor may be formed of a plurality of single sensor elements which can be connected electrically in different ways. In a calibration process, each of the sensor elements measures the magnetic field generated in the coil. In a conventional approach, a coil wire of the coil is arranged such that a homogeneous magnetic field is generated at the respective positions of each sensor element of the large sensor. This results in a higher length of the coil wire and thus a reduced effectiveness regarding calibration.
Document US 2011/0031960 shows a three-dimensional Hall sensor having asymmetrically distributed calibration wires provided at least over vertical Hall elements placed around a set of lateral Hall elements. A difference of different calibration field components is measured by averaging of the output signals of the partial sensors results.